Driving crank for piston engines



K. KUEHN DRIVING CRANK FOR PISTON ENGINES Filed Jan. 18, 1929 June 23,1931.

Patented June 23, 1931 PATENT OFFICE KARL KUEHN, OF COLOGNE, GERMANYDRIVING CRANK FOR, PISTON ENGINES Application filed January 18, 1929,Serial N0.'333,445, and in Germany January 25, 1928.

The usual driving crank for piston engines has the disadvantage toproduce at the dead points great momentum of fieXion in this crank. Inorder to remedy this disadvantage, it has been experimented to guidethe.

head of the connecting rod on one side in a fixed curved groove and onthe opposite side in a longitudinal groove of the crank of the engine.This arrangement permits one of the dead points between the piston andthe connecting rod to lead or lag with respect to the other one but,because of the form of the guiding way the length of the stroke isshortened and the power of engine reduced.

The object of the invention is to remedy this disadvantage by guidingthe'head of the connecting rod into a guiding groove having in thedirection of the piston stroke the shape of a pear slightly curved on apart of the The cylinder a into which slides the pis-' ton b may be thecylinder of a steam engine or the one of an internal combustion engine.The connecting rod a, coupled with the piston, is guided by apear-shaped guiding groove 6, forming a part of a fixed frame Theguiding groove 6 has in the direction of the longitudinal axle of theengine, that is to say in the direction of the piston stroke, the shapeof a pear and has a slight curve 9 at the upper part. The head of theconnecting rod also slides into the groove h of the crank 2' of thedriving shaft is.

In Fig. 1 the position of the upper dead point of the piston b, that isto say when the connecting rod 0 has reached its strokes end, the headof the connecting rod d is already on the beginning of the curvedguiding groove 9. According, the force P directed tdwards the bottom isdecomposed into two components P and P respectively tangent andperpendicular to the guiding groove. Whilst the perpendicular componentP is rendered null by reaction of the guiding groove, the tangentialcomponent P which moves the driving shaft with a levers arm Z, causesthe deviation of the crank z' and exercises by this fact, already at thedead point, a powerful rota-ting momentum upon the driving shaft. By theform of a pear and the curve 9 of the guiding groove, it is possible togive, for any position of the crank, a determined value to the rotatingmomentum. By making an adequate choice of the pearform of I the guidinggroove a shortening of the piston stroke is avoided and no lengthenedstop of the piston at the dead points is produced.

What I claim is: 1. In a piston engine, a rod with its foot connected tothe piston, means for guiding the head end of said rod including a fixedcurved cam groove and a crank connected loosely to the rod head, saidcam groove having an incurved part situated on the side corresponding tothe drive stroke of the active surface of the piston and beginninginfthe direction of rotation at a point located slightly in front of theline'of the dead points of said piston, said part forming a small anglewith the line of thedead points.

2. In a piston engine, a rod connected by its foot to the piston, meansfor guiding the head end of said rod including a hired curved cam grooveand a crank connected loosely to the head of said rod, said cam groovehaving an incurved part located on the side corresponding to the drivestroke of the active surface of the piston and beginning in thedirection of rotation at a point located s1ightly in front of the lineof the dead points of said piston, said part forming with the line ofthe tangent to the different points of said part forming with thedirection of the line of said dead points an angle, which angleincreases with the points of tangency taken successively in thedirection of rotation.

In testimony whereof I have aflixed my signature.

KARL KUEHN.

